Conventional arc furnaces are provided with a refractory brick lining covering the interior wall of the furnace vessel. This brick lining wears down in the course of the furnace operation because of the chemical and thermic stresses to which it is exposed. The part of the vessel wall above the melting zone has, therefore, been provided with cooling pipes lying closely adjacent to each other in the manner of a pipe coil for example. The surface structures consisting of pipes represent segment-type wall elements fastened to a support structure. This support structure is constructed as an installation at the melting zone which forms the vessel, refractorily lined and provided with a steel jacket, and consists of hollow bodies which are rectangular in their cross section, said bodies welded together with flat plates and with cooling liquid flowing through said hollow bodies.
Due to the voluminous welding operation involved, the manufacture of this support structure is expensive and time consuming. Lately the question of energy recovery in metal-melting furnaces, particularly arc furnaces, has greatly gained in importance. Up to the present, however, the cooling-water circulation has been regulated in such a manner that the cooling water was heated up without turning to steam.
The objective of the present invention is to develop the support structure of a metal-melting furnace in a simple manner so that said structure is capable of delivering cooling water which has absorbed a substantially higher degree of heat so that correspondingly more energy may be recovered from said water.
The present invention solves this problem in that the support structure is made of pipes forming a cage comprising horizontal rings superposed, in intervals, on each other and connected through pipes. The present invention is based on the recognition that a box-shaped support structure, consisting of structural elements which are rectangular in cross section, does not withstand the pressures caused by cooling water which is heated to a higher degree because the bursting limit of the rectangular "pipes" forming the structure is too low. In contrast, the present invention makes it possible to use conventional pipes for manufacturing the support structure, thus on the one hand, simplifying and lowering the cost of production, and yet, on the other hand, achieving substantially higher water temperatures because higher internal pressure is achievable.
The present invention is described with the aid of an embodiment example.